Electrical Systems and Energy Infrastructure Flashcards

Vocabulary based on lecture notes covering electrical circuits, emissions scopes, power infrastructure, battery technology, and modern grid concepts.

Scope 1: Direct Emissions

Emissions from sources the company directly owns or controls, such as burning fuel in company-owned vehicles, boilers, or furnaces.

Scope 2: Indirect Emissions from Purchased Energy

Indirect Emissions from Purchased Energy These are indirect emissions from the creation of electricity, steam, heating, or cooling that the company purchases for its own operations.

Examples:The electricity used to power a company's offices, factories, or data centers.The heat and cooling required for a company's buildings and facilities.

Scope 3: Other Indirect Emissions

Broad category including indirect emissions occurring in a company's value chain outside its direct control, such as upstream production of materials or downstream use of sold products.

Examples: Upstream activities: Emissions from the production of purchased goods and materials (e.g., metals for a car manufacturer), upstream transportation (e.g., transporting components to a factory), and employee commuting.Downstream activities: Emissions from the use of sold products (e.g., consumers cooking a product), and the end-of-life treatment of products (e.g., recycling or landfilling waste from products).Other examples include business travel, waste disposal, and capital goods.

Circuit

A closed, continuous pathway that allows electricity (electrons) to flow from a power source, through components, and back to the source. It requires a complete loop to function; if the path is broken (open circuit), electricity cannot flow.

Key Components of a Circuit

• Power Source: Provides voltage/energy (e.g., battery, outlet).

• Conductor: Material allowing electron flow, typically copper wires.

• Load: Device consuming power (e.g., light bulb, motor, resistor).

• Switch: Controls the circuit by opening or closing the path.

Key Concept

• Voltage (): The "push" that makes electricity flow, measured in volts.

• Current (): The flow rate of charge, measured in amperes (amps).

• Resistance (): Opposition to the flow of charge, measured in ohms ()

Voltage

The "push" or electrical potential difference that makes electricity flow, that drives electric charge to move through a circuit, measured in volts ($V$).

Requirement: Must have a difference in potential (voltage) between two points for current to flow. Think one end of a pipe higher than the other that causes the water to flow down.

Often compared to water pressure in a pipe, it represents the energy available to push current from one point to another, generated by sources like batteries.

Wall outlet supplies 120V AC. There is the voltage supplied to the thing, and the voltage it outputs or uses. Ie. a phone charger outputs 5-20v.

Many devices do use a transformer or transformer-like component to reduce the voltage, but not all modern electronics use a traditional transformer. Voltage conversion is one of the primary jobs of power electronics.

Current ($I$)

The flow rate of charge, essentially how many electrons flow past a point in a wire per second, measured in amperes (amps).

Resistance ($R$)

Opposition to the flow of charge, measured in ohms ($\Omega$).

Watts ($W$)

A unit of power measuring the rate at which energy is used or produced; calculated in simple circuits as $W = V \times A$.

K-kilo

$1,000$ watts.

M-mega

$1,000,000$ watts.

G-giga

$1,000,000,000$ watts.

Kilowatt-hour ($kWh$)

A measurement of energy used over time; for example, a $1,000\text{-watt}$ appliance used for one hour consumes $1\text{ kWh}$.

For batteries it depends how long the battery can discharge energy. So, a battery with a power capacity of 1 MW that can typically operate for 4 hours (duration) would have an energy capacity of 4 MWh battery (1 MW x 4 hours = 4 MW-hours).

Or a battery system has a power rating of 30 MW and an energy rating of 120 MWh. This means the battery can discharge for 4 hours.

Switchgear

An electrical device or assembly used to control, protect, and isolate electrical equipment in a power system, acting as a command center for distribution.

Power Grid

The system of power lines, transformers, and control systems that delivers electricity from generation sources to homes and businesses.

Power Electronics

A branch of electrical engineering using semiconductor switches (like diodes and transistors) to convert, control, and manage electrical power efficiently.

UPS (Uninterruptible Power Supply)

A device providing emergency backup power to equipment when the main power source fails, allowing for safe shutdown or switching to a generator.

Transformer

A device that changes the voltage level of electricity, either stepping it up for efficient long-distance transmission or down for safe home use.

Inverters

Devices that convert electricity from Direct Current ($DC$) into Alternating Current ($AC$).

Rectifiers

Devices that convert Alternating Current ($AC$) into Direct Current ($DC$), often used in battery chargers and electronics power supplies.

Direct Current ($DC$)

A steady, unidirectional flow of electricity from the positive to the negative terminal; the type of power produced and used by all batteries.

Peak Shaving

The practice of reducing the highest spikes in electricity demand to even out usage over time, lowering costs and reducing strain on the grid.

Load

Anything in an electrical system that consumes power, such as lights, motors, or HVAC units, measured in kilowatts ($kW$) or megawatts ($MW$).

Load Bank

A device that mimics an electrical load for testing purposes, allowing performance verification of generators or batteries without actual equipment.

UL (Underwriters Laboratories)

An independent global safety science company that tests and evaluates products to ensure they meet specific safety, quality, and performance standards.

Ion

An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

Cathode

The positive side of a battery during discharge where electrons arrive after doing work; the site of reduction (gain of electrons).

Anode

The negative side of a battery during discharge where electrons leave; the site of oxidation (loss of electrons).

Flow Battery

A battery that stores energy in tanks of liquid electrolyte, allowing the decoupling of energy and power for easier scaling of energy capacity.

Point of Common Coupling (PCC)

The physical location where a customer's private grid connects to the public utility network, acting as the demarcation point for responsibility and metering.

IEEE

The Institute of Electrical and Electronics Engineers, a leading consensus-building organization for advancing global technologies and standards.

IEEE 2030.6

A guide for monitoring and evaluating the effects and benefits of electric power grid customer demand response programs.

Power Quality

The measure of how closely voltage, frequency, and waveform match ideal standards to ensure electrical equipment operates correctly without degradation.

Power Harmonics

Distortions or "extra" frequencies in electricity that occur when the waveform isn't a smooth $60\text{ Hz}$ sine wave, often introduced by inverter-based equipment.

Distributed Energy Resource (DER)

Small-scale, localized power generation and storage technologies (like rooftop solar or batteries) located near the point of consumption.

Grid Forming

The ability of an inverter-based source to provide voltage and frequency support and operate independently of the main grid.

Grid Following

An inverter control strategy that synchronizes output with grid voltage and frequency; it depends on a stable grid and cannot operate off-grid.

Microgrid

A self-sufficient energy system serving a discrete footprint that is characterized as being local, independent (islanding capability), and intelligent.

Virtual Power Plant (VPP)

A cloud-based network of decentralized energy resources aggregated to operate as a single, flexible power plant using software to coordinate in real time.

Power Purchase Agreement (PPA)

A long-term contract where a developer installs and operates a renewable energy system on a customer's property and sells the power at fixed rates.

12kV Line

A medium-voltage electrical backbone distribution system that moves large amounts of electricity efficiently before being stepped down for building use.

Bidirectional Charging

Technology allowing electricity to flow two ways: into an EV to charge it, and out of the EV to power a home, devices, or the grid.

Feeder

A medium-voltage electrical power line that transmits electricity from a distribution substation to local distribution points or transformers.

Relationship between Power, Voltage, and Current

Power ($P$) is calculated as the product of Voltage ($V$) and Current ($I$) in an electrical circuit, expressed as $P = V \times I$.

If you want to deliver the same amount of power, you can either use: high voltage and low current, or low voltage and high current.

The wires themselves have electrical resistance. Whenever current flows through a wire, some energy is lost as heat. The higher the current, the greater the loss, at exponential levels. The higher voltage means much lower current for the same power, dramatically reducing transmission losses.

Thus, utilities use high voltage and low current.

Relationship between Current and speed

A lower current means slower movement of electrons, called drift velocity. They can move between a few millimeters per second in a household wire (taking hours to travel from light switch to bedside lamp), or a few centimeters per second.

Another speed is the electrical signal. When you flip a light switch, the lamp turns on almost instantly—not because electrons race from the switch to the bulb, but because the electric field that tells electrons to move propagates through the wire at 50-99% of the speed of light.

Another speed is the energy that powers the lamp. It travels with the electromagnetic field surrounding the wires, not by waiting for a particular electron to make the journey.

A good analogy is a long tube filled with marbles:

• Push one marble in one end.

• A marble pops out the other end almost immediately.

• No single marble traveled the whole length instantly; the push was transmitted through the line of marbles.